Where can I replace iPhone battery

I do not see any self repair options for the iPhone 11.

@yoel261:

Go to this web site for information about how to request battery service for your iPhone: iPhone Battery Service - Apple Support

For cost and availability, enter your model information in the "Get an estimate" box at the bottom. (It is best that you do this since sometimes contributors here forget this is an international forum and not everybody asking questions lives in the contributor’s country.)

For instructions on how to get your iPhone, iPad, or iPod touch ready for service click here --> Prepare your iPhone or iPad for service - Apple Support

I would Contact - Official Apple Support to set up hardware service if I where you

You can also order the tools you need to do a self service repair:

Self Service Repair - Apple Support